


Hilbert's Hotel of the Heart

by TheWhiteLily



Series: Watson's Woes July Writing Prompts 2017 [7]
Category: Sherlock (TV)
Genre: Acceptance, Domestic, Gen, Grief/Mourning, Mathematics, Parentlock, families
Language: English
Status: Completed
Published: 2017-07-09
Updated: 2017-07-09
Packaged: 2018-11-29 19:20:51
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,486
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11447397
Author URL: https://archiveofourown.org/users/TheWhiteLily/pseuds/TheWhiteLily
Summary: John comes home to find Mummy Holmes helping Rosie with her maths homework.





	Hilbert's Hotel of the Heart

**Author's Note:**

> JWP #8: Everyone Loves Sharing Their Expertise. All of us have something we've learned about or practiced a great deal. Whether it's knitting, or horseback-riding, or a particular performing group, use one of your own hobbies or interests as the inspiration for today's work. And don't forget to tell us what it is in the notes!

John’s footsteps slowed as he came towards the top of the stairs, hearing familiar voices echoing from behind the door. He hovered on the verge of entering for a few moments, before deciding to go through to the kitchen instead, listening to the voices as he flicked on the kettle and pulled out five cups, setting them up for tea.

Mrs Hudson was away with her sister on some mad world trip, and while Sherlock would never have forgotten to pick Rosie up from school, the chances of him actually having offered their visitors a drink were still minimal.

“Well, say you wanted to know the area of… the surface of the water in the glass, when I tilted it onto its side, like this.”

“It’s… it’s _like_ a circle, isn’t it, Grandma Holmes?” came Rosie’s voice uncertainly. “And I know the area of a circle, but… this is bigger?”

“Ah, but how much bigger?”

“Well…” Rosie paused for a moment, obviously thinking. “It’s the same width side to side, that’s easy. And we could measure how long it is the other way, that’s easy too.”

The kettle clicked off, and John poured the water over the teabags, still listening.

“Hmmm, width, by length,” said Mrs Holmes thoughtfully, and there was the sound of paper rustling. “Like a rectangle, like this? How would that change the formula, do you think?”

When he opened the door to the living room, Rosie was frowning at a piece of paper on the desk in front of her, tongue tilted out to the side between her teeth, a sparkling pink gel pen clutched in her hand.

John dropped a kiss onto Rosie’s forehead, who barely noticed, and smiled at Mrs Holmes seated beside her as he crossed to perch on the arm of Sherlock’s chair. Mr Holmes was sitting in John’s chair, opposite his son, reading glasses perched on his nose. He favoured John with a distracted nod before returning his full attention to the paper.

“Well, _this_ would have been the radius, if it was a circle, only _this_ would have been, too,” Rosie was telling Mrs Holmes earnestly.

“How long have they been going?” John murmured.

“Forty-five minutes,” Sherlock said, turning a page in _Forensics Quarterly_ with an affected lack of interest.

John looked the desk where Rosie’s school books and problem sheets had been spread out among an explosion of scribbled on pieces of paper and rainbow pencil-cases.

“They will eventually teach her this stuff in school, you know,” said John. “Your mother doesn’t actually have to come here to help Rosie with her maths homework.”

“You think she’s here because she thinks she has to be?” asked Sherlock dryly. “She was disappointed to find there was only one sheet of maths homework, so they’ve started making up their own worksheets to show Miss Stubbins. They’ve made it from elementary multiplication, all the way through trigonometry and onto conic sections, although I expect that’s only a minor stop on the way to calculus. I just hope they don’t reach the aleph numbers, or they really will be here forever.”

Sherlock’s father gave a snort.

“I heard that,” said Mrs Holmes without looking around. “You’re lucky Mikey’s taking us to a play this evening, that’s all I can say, Sherlock; we’ll have to save the infinite hotel for another day. Go on, dear,” she directed at Rosie.

John shook his head in disbelief, and turned his attention back to his daughter

“So, the _pi_ ’s there because it’s curvy so it’s not _quite_ four quarters,” said Rosie earnestly. “And the squared _was_ there because each quarter’s a square, but now they’re not squares, they’re rectangles, so it’s that way times that way instead—this is obvious, Grandma Holmes, why don’t they teach this in my class?”

“You mustn’t ask me, dear,” laughed Mrs Holmes. “I never understood _that_!”

“She never understood it!” echoed Mr Holmes in amusement.

“Oh, shush, you,” she said, exchanging a fond look with him. “Apparently people think it’s hard, Rosie,” she explained.

“Well, people are idiots!” scoffed Rosie.

“None of that, please Rosie,” reminded John, trying to suppress a laugh while shooting Sherlock an accusatory glare. They _were_ trying to limit that kind of talk in front of her; the problem was, both of them could tell when he _actually_ thought one of the habits she’d picked up from Sherlock was cute. At least it was in this, the kind of company that wouldn’t take offence at her pale imitation of Sherlock’s rudeness.

“Sorry Dad,” mumbled Rosie guiltily. “But Grandma Holmes, what’s the infinite hotel? Can’t you just tell me quickly? Look, we haven’t written on this page of my book at all!”

John shook his head, and went back into the kitchen to rescue the tea before it overbrewed.

He’d been so worried, after Mary was gone, about how he could ever cope with raising his daughter to be a young woman who would do her mother proud. How Mary could have been so blind as to miss seeing who John really was, how completely unprepared, how utterly unfit for the job he was. The task had seemed overwhelming—insurmountable—and in the depths of his grief, inevitably doomed to the devastating failure that had seemed at that point to be dogging his steps ever since Afghanistan.

Going on as John had been, he’d probably been right.

He’d dithered for months over moving back to Baker Street, until the message Mary had left made it clear he had her blessing. There were any number of reasons it could have been a terrible idea—not least among them that he had to be realistic about the fact that, as difficult as dating had ever been while living with Sherlock, in combination with his responsibilities as a single father, moving back into 221B would mean giving up any hope of finding Rosie a new mother, ever again.

Gone was any hope of filling that void in Rosie’s life—not the void of a parent, of course, because she had John, at least she did now that John had substantially sorted himself out. And, although it still sometimes rather surprised John how much, she had Sherlock as well.

John had mourned the tragedy that was Mary’s death in so many different ways—he’d mourned the woman he’d laughed with, the woman he’d argued through what to do with, the woman who’d stood with him against Sherlock, who’d stood with Sherlock against him, the woman he’d drunk tea in bed with in the mornings, the woman he’d been surprised by too many times, but whom he’d never stopped loving—but the one thing which had lingered longest was his grief for Rosie’s sake, for the woman whom Rosie would never know and learn from in the way that _she’d_ deserved to.

For a while, John had become hyperaware of every female drifting in and out of Rosie’s life, examining each one for what Rosie might take from them, whether there was any combination of qualities that would add up to mean she wasn’t missing out on what she should have had.

Of course, many young girls grew up fine without a strong female role model in their home. And of course Rosie had teachers, and there was Mrs Hudson and Molly, who had both more than stepped in to fill the breach. It had been wonderful to see Mrs Holmes, too, seeming to adopt Rosie as the closest thing, considering her three odd children, to a natural grandchild that she was ever likely to have.

“But, if it’s _full_ , how can it take in more guests?” drifted back Rosie’s confusion from the living room.

Mary had been a force to be reckoned with, and even if nothing and no one could replace her—her wry humour, her quiet determination, her unshakable self-confidence, her warmth, and fierce love—it was what it was.

And what it was, was filled to the brim with love; full of people, men and women both, who’d gathered around Rosie to fill that void her mother had left in her life.

Mary had known who John really was, flaws and all, and she’d trusted him with Rosie—trusted he and Sherlock both—not as pale substitutes for herself, but as the family her child needed to grow and be happy. Trusted them and the family they’d drawn around themselves to protect her, to guide her, to teach her what they knew: deduction and medicine and policing and baking and mathematics and self-reliance and determination and fierce, _fierce_ love—and no little girl could be missing out, who had all of that.

As he finished making the tea, John listened to Mrs Holmes chatter, explaining about the hotel that could take in infinitely more guests without ever running out of rooms.

And he hoped—he was _sure_ —that Mary would be proud of them.

**Author's Note:**

> I’ve always been a maths-lover, in part because my mother is a brilliant mathematician and my memories of learning various concepts are filled with the shared joy of discovery. Maths is love. <3
> 
> [Hilbert’s hotel](https://en.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel) is a thought experiment which aids in understanding the [aleph numbers](https://en.wikipedia.org/wiki/Aleph_number), or different types of infinity, which are a favourite topic of discussion of my children's _other_ grandparent with a postgraduate degree in mathematics. It seems to be somewhat of an ironic truism, that once you get a mathematician talking about infinity, you _will_ be there forever.


End file.
